很多時候由于異常或程序錯誤會導致個別進程占用大量系統資源，需要結束這些進程，通常可以使用以下命令Kill進程:
alter system kill session 'sid,serial#';

但是此命令釋放資源極為緩慢，具體可以參考:Oracle中Kill session的研究.
為了更快速的釋放資源，通常我們使用如下步驟來Kill進程:
1.首先在操作系統級kill進程
2.在數據庫內部kill session
這樣通常可以快速中止進程，釋放資源。

今天就遇到這樣一個案例，其他朋友在數據庫里kill session,可是長時間仍無效果:
[oracle@danaly ~]$ sqlplus "/ as sysdba"

SQL*Plus: Release 10.2.0.1.0 - PRoduction on Thu Oct 27 11:09:50 2005

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, Oracle Label Security, OLAP and Data Mining Scoring Engine options

SQL> select sid,username,status from v$session;

       SID USERNAME                       STATUS
---------- ------------------------------ --------
....
       154 SCOTT                          KILLED
...

30 rows selected.

那按照我前面提到的步驟，首先查詢得到該session對應的OS進程號:
SQL> select 'kill -9 '||spid from v$process where addr = (select paddr from v$session where sid=&sid);
Enter value for sid: 154
old   1: select 'kill -9 '||spid from v$process where addr = (select paddr from v$session where sid=&sid)
new   1: select 'kill -9 '||spid from v$process where addr = (select paddr from v$session where sid=154)

'KILL-9'||SPID
--------------------
kill -9 22702

SQL> !

在操作系統級kill該進程:
[oracle@danaly ~]$ ps -ef|grep 22702
oracle   22702     1  0 Oct25 ?        00:00:02 oracledanaly (LOCAL=NO)
oracle   12082 12063  0 11:12 pts/1    00:00:00 grep 22702
[oracle@danaly ~]$ kill -9 22702
[oracle@danaly ~]$ ps -ef|grep 22702
oracle   12088 12063  0 11:12 pts/1    00:00:00 grep 22702
[oracle@danaly ~]$ exit
exit

SQL> select sid,username,status from v$session;

       SID USERNAME                       STATUS
---------- ------------------------------ --------
...
       154 SCOTT                          KILLED
...

30 rows selected.

SQL> select sid,serial#,username from v$session where sid=154;

       SID    SERIAL# USERNAME
---------- ---------- ------------------------------
       154      56090 SCOTT

再次在數據庫中kill該session,并指定immediate選項:
SQL> alter system kill session '154,56090' immediate;

System altered.

SQL> select sid,serial#,username from v$session where sid=154;

no rows selected

此時該進程被迅速清除。